1. Field of the Invention
The present invention relates to a system for measuring human body balance signals and a method for analyzing the same, in particular, a system used to evaluate the sense of balance, mainly by measuring the features of balance-related physiological signals from the human body to establish risk assessment indicators for falling down.
2. Brief Description of the Prior Art
According to statistical results, senior citizens have a higher rate of falling down than other age groups. Fall-related injuries are the primary cause of hospitalization and the second highest cause of accidental death for seniors. If an elderly person falls down, body and mental recession become faster because of slower recovery, lack of exercise when in bed and less body movement. Moreover, the elderly usually will also need long-term assists from other family members or care-takers which can cause burdens to the family resulting in emotional and relationship problems.
To prevent elderly people from falling down, the reasons for falling must first be studied. Falling down is a result of loosing body balance. The causes for this are many but in most cases for the elderly; it is because of unintentional loss of balance. As a result, it becomes important to regularly detect the sense of body balancing and make proper adjustments to thereby effectively prevent falling accidents.
All the following articles point out current balance measuring systems which are suitable for lab experiments but not suitable in daily use:
(1) U.S. Pat. No. 5,388,591 (Article 1)
Article 1 mentions maintaining an upright position involves complex senses like vision and hearing which affect the sense of balance. This human posture control system first measures and calculates the COP (center of pressure) movement on feet and time intervals and with changes in vision and hearing to study if the sense of balance is improved. This invention requires complex theories and measures many sensing signals that are usually obtained in a lab. It is difficult for the public to use such a system at home and is not suitable for the general public.
(2) U.S. Pat. No. 5,627,327 (Article 2)
Article 2 mentions standing on an unstable platform for measuring balance. Because of the changes on the platform, the patients' adaptability must rapidly adjust to adapt to the moving platform. The system calculates the samples' sense of balance with monitors and surveillance video systems. This method takes a lot of time and had space limitations. Also, the method requires someone to stand on an unstable platform. This method is not suitable the elderly and certain other members of the public.
(3) U.S. Pat. No. 5,830,158 (Article 3)
Article 3 mentions a system similar to the one in Article 2 but differs in using a sensor under the unstable platform that sends the patient's standing position to a computer for it to display on a monitor in front of the patient. The patient on the test must try to move his COG (center of gravity) to the designated destinations. The sense of balance is analyzed from the data collected. This method also need a lot of time, has space requirement problems, and is not suitable for the elderly.
(4) U.S. Pat. No. 6,063,046 (Article 4)
Article 4 is about a system composed of force sensors, body movement sensors, and EMG (electromyography) electrodes. The force sensors provide the toe-end and heel-end center of pressure change before and after the measurement to the processor. The body movement sensors convert the signals they collected to detail angular position and velocity data for the processor. The EMG electrode signals are amplified to provide muscle movement data to the processor. The processor combines these three data for body balance signals. The drawback is these 3 sensors are expensive and can only be used experimentally but cannot be widely adopted.
(5) U.S. Pat. No. 6,237,256 (Article 5)
Article 5 is about a balance measuring method for standing on a large moveable platform blindfolded. The platform will suddenly move forward, backward, to the right, or to the left. The three force sensors on the large platform and the cameras record data to analyze the subject's sense of balance. Though the large platform has safety handrail installed, this system is still dangerous for the elderly and not suitable for them.
(6) U.S. Pat. No. 6,561,991 (Article 6)
(7) U.S. Pat. No. 6,607,497 (Article 7)
Articles 6 and 7 are similar. They both have a non-rigid supported vibrating platform whose acceleration sensor records the tester's body movement, uses vibration to measure muscle and skeleton, then the vibration and frequency data are changed into vibration spectra for analysis and evaluation. The vibration on this platform may be uncomfortable for the elderly and so the collected data may not be accurate.
(8) U.S. Pat. No. 7,492,268 (Article 8)
(9) U.S. Pat. No. 7,292,151 (Article 9)
Articles 8 and 9 provide an interactive monitoring system with sensors and input control, using wireless communication and monitoring equipments to receive signals and automatically responds with specific answers. This invention is directed to evaluating sports so it is more helpful in observing athletes but not for use by others.
(10) U.S. Pat. No. 5,919,149 (Article 10)
Article 10 is about a system based on balance calculation and how people would react to maintain the stability of a body position and speed when they are not stable. This invention uses light-weight and durable vibration sensors and speed sensors attached to the upper body. Improvement of balance is determined by the angular movements and speeds signals from the sensors. This method needs to attach sensors on the body during the test and they are not easily carried. Multiscale entropy (MSE) could instead be more accurate than simply using angular speed for analysis.
(11) Republic of China (Taiwan) Patent 200821015 (Article 11)
Article 11 is a dynamic posture balance training system composed of foundation and tilting platform controlled by power and vibrating mechanism to move and vibrate the training platform. A sensor is configured to sense the down pressing weight of the user, and a receiving module is configured to receive the signals from the sensor for analyzing the different center of pressure under different motions like moving, vibrating, and turning. This patent needs a person standing on a moveable platform and then calculates the data with the platform moving. Accordingly, the system is not suitable for the elderly.
(12) Republic of China (Taiwan) Patent 094130876 (Article 12)
Article 12 has equipment to cause voltage change but does not further analyze the produced signals for human body center of weight offset. As will be explained, the present invention is better for it measures and collects the platform data, uses program written in MatLab to transfer the data into a diagram for a human body movement offset, then use MSE (multiscale entropy) to analyze the data, and numerically present the balance conditions of the tester.
(13) Republic of China (Taiwan) Patent 096217876 (Article 13)
Article 13 uses a three-axis accelerometer to measure voltage change which is different from our way of using load cell. Our amplifying circuit board also has the filtering function to reduce noise. The analysis method is different too as will be explained. Article 13 uses acceleration as the quadratic differential of displacement to determine body movement which is not very accurate. The present invention directly analyzes the offset of center of weight which is a better solution.
According to the above mentioned thirteen (13) articles, current systems that measure the sense of balance are used in the lab for experiments and they are expensive and complicated to operate. The manufactures would not mass produce this precision equipment and it could not be easily afforded and accessible for the public. Because it takes a lot of time for treating the balancing problem, patients must often go to major hospitals or medical centers for detecting the sense of balance. This can become a transportation and cost burden for patients so that treatment could not be maintained thereby resulting in the interrupt of the treatment.
The known current practice has a lot of drawbacks, is not a good design, and must be improved.